Method of Forming Metal Oxide Hardmask

ABSTRACT

A method of forming a metal oxide hardmask on a template includes: providing a template constituted by a photoresist or amorphous carbon formed on a substrate; and depositing by atomic layer deposition (ALD) a metal oxide hardmask on the template constituted by a material having a formula Si x M (1-x) O y  wherein M represents at least one metal element, x is less than one including zero, and y is approximately two or a stoichiometrically-determined number.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 13/333,420,filed Dec. 21, 2011, which claims the benefit of U.S. ProvisionalApplication No. 61/427,661, filed Dec. 28, 2010, each disclosure ofwhich is herein incorporated by reference in its entirety for someapplicable embodiments disclosed herein.

The applicant herein explicitly rescinds and retracts any and all priordisclaimers or disavowals made in any parent, child or relatedprosecution history with regard to any subject matter supported by thepresent application.

BACKGROUND

The present invention relates to semiconductor integrated circuitmanufacturing and, more particularly to a method of forming a hardmask,particularly a spacer film.

DESCRIPTION OF THE RELATED ART

Photolithography technology has recently faced difficulty of formingpatterns having pitches smaller than the submicron level. Variousapproaches have been studied, and one of the promising methods isspace-defined double patterning (SDDP) which makes it possible to createnarrow pitches beyond limitations of conventional lithography such aslight source wavelength and high index immersion fluid. Generally, SDDPneeds one conformal spacer film and hardmask template wherein theconformal spacer film is deposited on the template normally havingconvex patterns. A silicon oxide layer is commonly used as a conformalspacer, and a hardmask template is typically constituted by photoresist(PR) or amorphous carbon (a-C) prepared by a spin-on or CVD process.

As discussed blow, the present inventors have recognized severalproblems in SDDP and developed solutions thereto, which solutions canalso be applicable to general patterning processes. Thus, the presentinvention relates to improvement on general patterning processes using ahardmask, and particularly on SDDP.

Any discussion of problems and solutions involved in the related art hasbeen included in this disclosure solely for the purposes of providing acontext for the present invention, and it should not be taken as anadmission that any or all of the discussion was known at the time theinvention was made.

In SDDP process flow, it is required for a spacer film to beetch-selective relative to a base film which is typically a bottomantireflective coating (BARC) or a hardmask having BARC functions. Thebase film is typically constituted by a material such as SiO, SiOC,TiN-HM, etc. which is typically formed by CVD. Typically, as a spacerfilm, a low-temperature SiO film (LT-SiO) which is formed by atomiclayer deposition (ALD) at low temperatures is used. However, the LT-SiOdoes not have sufficient etch (dry and/or wet) selectivity relative to abase film, thereby causing unexpected critical dimension (CD) changes orthe like.

Most metal oxides/nitrides are known to be etch-selective to SiO. Somemetal oxides are hardly etched by dry etch. That is a significantconcern for semiconductor integration and also reactor cleaning. Forexample, Al₂O₃ is one of the promising candidate materials, because ithas a 100% conformal film profile even at room temperature and has highetch selectivity relative to a base film. However, Al₂O₃ is known to behardly etched by dry etch and/or wet etch, prohibiting Al₂O₃ from beingused as a spacer material.

Further, it is required that a spacer film be formed at low depositiontemperatures such as less than 150° C. when the template is constitutedby photoresist, or less than 300° C. when the template is constituted byamorphous carbon. Otherwise, the template may be damaged by heat duringthe deposition of the spacer film, and additionally, if the temperatureis as high as 400° C., diffusion or migration of Cu or B into a devicesuch as an insulation film, wiring, or transistor may occur. Namely, thespacer film needs to be compatible with the template. Also, it isrequired for the spacer film to be substantially 100% conformal and havesubstantially no pattern loading effect (e.g., substantially the samethickness on sidewalls even when the density of patterns or pitch ofpatterns is different). Conventional spacer films do not satisfy theabove criteria. Additionally, a metal such as V or Nb which is notcommonly used in the semiconductor processing processes may not be agood candidate.

Many groups have studied conformal SiN deposition, but their attemptshave not yet been successful to provide a solution to obtainingconformal SiN film. At a low temperature such as 400° C. or lower, a SiNprocess fails to form a conformal film (“conformal” refers to a Ts/Tt>about 95% wherein Ts and Tt are thicknesses on a sidewall and topsurface, respectively), and the low-temperature SiN process is performedat an extremely low-growth rate such as less than 0.1 nm/min.

The present inventors have recognized still another problem in SDDPwhich is a problem of patterned spacer collapsing. FIGS. 1A to 1D are aschematic representation illustrating a part of the SDDP sequence of (a)photoresist (PR) patterning (FIG. 1A), (b) SiO deposition by PE-ALD(FIG. 1B), (c) reactive ion etch (RIE) (FIG. 1C), and (d) PR ashing(FIG. 1D). This figure is solely for addressing the above problem anddoes not necessarily represent conventional technology. As shown inFIGS. 1A to 1D, in step (a), PR 2 (template) is formed in a pattern on abase film 1 (BARC or hardmask), under which a target film 4 to be etchedis formed. In step (b), a spacer film 3 is deposited on and covers PR 2and the base film 1. In step (c), anisotropic spacer etching isconducted, and as a result, the top of PR 2 and the base film 1 areexposed, thereby forming an exposed PR 2′ and a spacer 3′. In step (d),the exposed PR 2′ is removed by etching, and as a result, the spacer 3′collapses, deteriorating the pattern.

The main cause of collapse appears to be capillary force during theprocess of drying residual rinse and water after the template (PR 2′) isremoved by ashing. The pattern collapse problem becomes more seriouswhen patterns are as narrow as the submicron level and have higheraspect ratios such as one or higher. FIG. 2 is a schematicrepresentation illustrating capillary force generated during the dryingprocess. Capillary force σ_(max) (maximum stress exerted on the spacer)is expressed by the following equation (Y. Matsui et al., ISSM 2010,Tokyo, PO-O-103):

$\sigma_{\max} = {\frac{6\gamma \; \cos \; \theta}{D}\left( \frac{H}{W} \right)^{2}}$

γ: surface tension of H₂O

θ: H₂O contact angle

D: space width

H: height

W: width

In the figure, a spacer 21 is formed on a base film 23, and a space 22between the spacers 21 is filled with water. The top of filled water isconcave as it is being dried. The maximum stress exerted on the spacer21 strongly depends on the aspect ratio (H/W) and the contact angle (A).

One approach to solve this problem is using a hydrophobic material so asto reduce capillary force. However, it is very difficult to maintainhydrophobicity of the surface of the spacer for SDDP because even if thehydrophobic material is used, after ashing (typically by exposing thetemplate to an oxidant plasma such as an oxygen plasma, N₂O plasma, andCO₂ plasma, the surface is easily changed to hydrophilic becausehydrophilic O—H is easily generated on the oxidized surface after airexposure.

SUMMARY

As discussed above, the present inventors have recognized severalproblems in SDDP and developed solutions thereto. The solutions can alsobe applicable to general patterning processes. Some embodiments of thepresent invention provide solutions to at least one of the aboveproblems, and some embodiments provide solutions to all of the aboveproblems.

An embodiment of the present invention provides a method of forming ametal oxide hardmask on a template, comprising: (i) providing a templateconstituted by a photoresist or amorphous carbon formed on a substrate;and (ii) depositing by atomic layer deposition (ALD) a metal oxidehardmask on the template constituted by a material having a formulaSi_(x)M_((1-x))O_(y) wherein M represents at least one metal element, xis less than one including zero, and y is approximately two or astoichiometrically-determined number. The “hardmask” refers to amaterial used in any semiconductor processing as an etch mask in lieu ofpolymer or other organic “soft” materials (target films) which tend tobe etched easily by oxygen, fluorine, chlorine, or other reactive gasesto the extent that a pattern defined using the “soft” mask can berapidly degraded during plasma etching as compared with the hardmask.

In some embodiment, the metal oxide hardmask is a spacer film. In someembodiments, the spacer film is for spacer-defined double patterning(SDDP), and the method further comprises performing SDDP after the stepof depositing the spacer film on the template.

In some embodiments, M is a metal whose fluoride has a vapor pressure ofmore than 100 Pa at a temperature for cleaning a reactor used fordepositing the metal oxide hardmask. In some embodiments, M is Ti, W, orTa. In some embodiments, M is Ti. In some embodiments, the materialconstituting the metal oxide hardmask is TiO₂.

In some embodiments, the ALD is plasma enhanced ALD (PE-ALD). In someembodiments, the ALD is performed at a temperature of 300° C. or lowerfor the template constituted by the amorphous carbon or at a temperatureof 150° C. or lower for the template constituted by the photoresist. Insome embodiments, the ALD is performed under conditions substantiallyequivalent to those set for a SiO₂ hardmask constituted by SiO₂, whereina gas containing M is used in place of a gas containing Si for the SiO₂hardmask. In some embodiments, the metal oxide hardmask has an elasticmodulus at least three times higher than that of the SiO₂ hardmask, anda hardness at least two times higher than that of the SiO₂ hardmask. Insome embodiments, the metal oxide hardmask has a dry etch rate lowerthan that of the SiO₂ hardmask and a wet etch rate comparable to that ofstandard thermal oxide.

In some embodiments, the substrate has a base film formed under thetemplate, which base film is constituted by silicon oxide. In someembodiments, the template has a convex pattern constituted by thephotoresist or amorphous carbon, said convex pattern having a width ofless than one micron meter and a ratio of height to width of one orhigher.

For purposes of summarizing aspects of the invention and the advantagesachieved over the related art, certain objects and advantages of theinvention are described in this disclosure. Of course, it is to beunderstood that not necessarily all such objects or advantages may beachieved in accordance with any particular embodiment of the invention.Thus, for example, those skilled in the art will recognize that theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

Further aspects, features and advantages of this invention will becomeapparent from the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will now be described withreference to the drawings of preferred embodiments which are intended toillustrate and not to limit the invention. The drawings areoversimplified for illustrative purpose and are not necessarily toscale.

FIGS. 1A to 1D is a schematic representation illustrating a part of theSDDP sequence of (a) photoresist (FIG. 1A), (PR) patterning (FIG. 1A),(b) SiO deposition by PE-ALD (FIG. 1B), (c) reactive ion etch (RIE)(FIG. 1C), and (d) PR ashing (FIG. 1D).

FIG. 2 is a schematic representation illustrating capillary forcegenerated during the drying process.

FIGS. 3A and 3B is a schematic representation illustrating in-situfooting reduction where (a) reactive ion etch (RIE) (FIG. 3A) and (b)ashing (FIG. 3B) are conducted.

FIGS. 4A to 4G schematically illustrate SDDP processes wherein (a) is aschematic cross sectional view of pre-patterned features formed on ahardmask (FIG. 4A), (b) is a schematic cross sectional view of conformalspacer deposition (FIG. 4B), (c) is a schematic cross sectional view ofanisotropic spacer etching (FIG. 4C), (d) is a schematic cross sectionalview of removal of the pre-patterned features (FIG. 4D), (e) is aschematic cross sectional view of pattern transfer by anisotropicetching (FIG. 4E), (f) is a schematic cross sectional view oftransferred pattern profile (FIG. 4F), and (g) is a schematic crosssectional view of removal of the spacer (FIG. 4G).

FIG. 5 illustrates elastic modulus and hardness of each spacer filmdeposited in the examples.

FIG. 6 is a schematic representation of a PE-ALD apparatus fordepositing a spacer film usable in one embodiment of the presentinvention.

FIG. 7 illustrates a process sequence of one cycle of PE-ALD accordingto an embodiment of the present invention.

FIG. 8A is a schematic representation of pattern transfer and targetetching according to a comparative example. FIG. 8B is a schematicrepresentation of pattern transfer and target etching according to anembodiment of the present invention.

FIG. 9 is a schematic representation of pattern transfer and targetetching using space defined double patterning (SDDP) according to anembodiment of the present invention.

FIG. 10 is a graph illustrating the relationship between refractiveindex (at 633 nm) and average growth rate (nm/cycle) in relation to theALD cycle ratio of TiO₂/(TiO₂+SiO₂) according to embodiments of thepresent invention.

DETAILED DESCRIPTION

In this disclosure, “gas” may include vaporized solid and/or liquid andmay be constituted by a mixture of gases. In this disclosure, thereactant gas, the additive/carrier gas, and the precursor may bedifferent from each other or mutually exclusive in terms of gas types,i.e., there is no overlap of gases among these categories. In someembodiments, “film” refers to a layer continuously extending in adirection perpendicular to a thickness direction substantially withoutpinholes to cover an entire target or concerned surface, or simply alayer covering a target or concerned surface. In some embodiments,“layer” refers to a structure having a certain thickness formed on asurface or a synonym of film. Further, “a” refers to a species or agenus including multiple species. In this disclosure, any definedmeanings do not necessarily exclude ordinary and customary meanings insome embodiments. In the disclosure, “substantially higher”,“substantially different”, etc. refer to a difference of at least 10%,50%, 100%, 200%, 300%, or any ranges thereof, for example. Also, in thedisclosure, “substantially the same”, “substantially equivalent”,“substantially uniform”, etc. refer to a difference of less than 20%,less than 10%, less than 5%, less than 1%, or any ranges thereof, forexample. The numerical numbers applied in examples may be modified by arange of at least ±50% in other conditions, and further, in thisdisclosure, any ranges indicated may include or exclude the endpoints.In the present disclosure where conditions and/or structures are notspecified, the skilled artisan in the art can readily provide suchconditions and/or structures, in view of the present disclosure, as amatter of routine experimentation.

In some embodiments, in order to solve at least one or all of theproblems discussed above in patterning processes using a hardmask, ahardmask material is selected. In some embodiments, a hardmask materialis selected from candidate materials using at least one or all of thefollowing criteria, for example: a material has high mechanicalstrength, and has a low dry and/or wet etch rate, but it can be etchedby fluorine gas, and its fluoride is not solid at a reactor-cleaningtemperature, and further, it can be deposited by ALD at low temperaturessuch as 400° C. or lower.

In some embodiments, hardmask materials can be selected using at leastone or all of the following criteria:

1) A hardmask material has a higher mechanical strength than that of aconventional SiO hardmask. For example, the hardmask formed by ALDconstituted by the material has an elastic modulus which issubstantially higher than that of a conventional SiO hardmask formed byALD at a low temperature, e.g., 150° C., and which is at leastsubstantially equivalent to that of a conventional SiN hardmask formedby ALD at a low temperature, e.g., 150° C. Also, the hardmask formed byALD constituted by the material has a hardness which is substantiallyhigher than that of a conventional SiO hardmask formed by ALD at a lowtemperature, e.g., 150° C., and which is comparable to that of aconventional SiN hardmask formed by ALD at a low temperature, e.g., 150°C.

2) The hardmask material having a higher chemical resistance (low dryetch rate) than a conventional SiO hardmask. For example, the hardmaskformed by ALD constituted by the material has a dry etch rate (NF₃ at100° C.) which is substantially lower than that of a conventional SiOhardmask formed by ALD at a low temperature, e.g., 150° C., and which isalso lower than that of standard thermal oxide. Also, the hardmaskformed by ALD constituted by the material has a wet etch rate (DHF at1:100) which is substantially lower than that of a conventional SiOhardmask formed by ALD at a low temperature, e.g., 150° C., and which issubstantially comparable to that of standard thermal oxide.

3) The hardmask material contains at least one type of metal element,and oxygen and/or nitrogen. The material may be expressed by a formulaSi_(x)M_((1-x))O_(y) wherein M represents at least one metal element, xis less than one including zero, and y is approximately two or astoichiometrically-determined number. For example, titanium oxide (e.g.,TiO₂) and titanium silicon oxide (e.g., TiSiO₄), are included.

4) The hardmask material is constituted by a metal oxide (e.g., TiO₂)and a silicon oxide (e.g., SiO₂, non-metal silicon oxide) so as toeffectively adjust a refractive index and a growth rate. In order to mixa metal oxide and a silicon oxide, the following methods can beperformed in some embodiments: depositing thin films of the metal oxideand thin films of the silicon oxide alternately (each film having athickness of about 3 nm or higher); depositing a film by introducing amixture of precursors for the metal oxide and the silicon oxide; ordepositing a film by alternately introducing a precursor for the metaloxide and a precursor of the silicon oxide. For example, a hardmask(metal silicon oxide, e.g., Ti_(x)Si_((1-x))O₂, 0<x≦1) can be formed byalternately depositing a metal oxide film and a silicon oxide film byALD at a certain cycle ratio (a ratio of cycles for the metal oxide filmto cycles for the silicon oxide film), wherein the growth rate of thesilicon oxide is about 2.5 times higher than that of the metal oxide,and the refractive index of the silicon oxide is lower than that of themetal oxide, so that by adjusting the cycle ratio, the growth rate andthe refractive index of the resultant hardmask can be adjusted. Forexample, when the cycle ratio is one (i.e., one cycle for the metaloxide film and one cycle for the silicon oxide film are alternatelyperformed), the composition ratio of metal oxide to silicon oxide in thehardmask is about 1/2.5 since the growth rate of the silicon oxide isabout 2.5 times higher than that of the metal oxide. By adjusting thecycle ratio, the proportion of metal oxide relative to the mixture ofmetal oxide and silicon oxide can vary from over 0% up to 100%.

5) The hardmask material contains at least one metal element, Si, andoxygen and/or nitrogen to tune optimal mechanical strength and dry etchrate. In some embodiments, this type of film can be formed by themethods disclosed in U.S. Pat. No. 7,824,492, the disclosure of which isherein incorporated by reference.

6) The hardmask can be formed by process steps including the stepsdescribed below by using the same reactor as that for forming a targetfilm, a base film, and a template. This series of steps can be performedcontinuously. In the above, “continuously” refers to without breaking avacuum, without interruption as a timeline, without moving thesubstrate, or immediately thereafter, as a next step. Although thehardmask can be deposited by ALD whereas the target film and base filmcan be deposited by CVD, these reactions can be accomplished in the samereactor.

6-1) Step of evaporating water from a template by baking: The templateis subjected to heat which is subsequently generated by exposing thetemplate to an inactive gas (e.g., He, Ar, or N₂) plasma or radicals, soas to evaporate water adsorbed on a surface of the template in a cleanroom outside the reactor, wherein the amount of adsorbed water dependson how long the template is exposed to air in the clean room.

6-2) Step of trimming and/or footing reduction using anoxygen-containing gas (e.g., N₂O or CO₂).

6-3) Step of depositing an adhesion layer on a base film or treating asurface of the base film by a plasma in order to enhance adhesionbetween the hardmask (spacer) and the base film.

6-4) Step of depositing a spacer film by ALD (which is described later).

6-5) Step of post treatment: The spacer film can be treated by posttreatment such as thermal annealing, plasma treatment, UV irradiation,radical exposure by using remote plasma, in order to prevent moistureadsorption.

7) The hardmask is formed by ALD. The deposition methods include plasma(both remote and in-situ) generation to activate reactant to causedeposition. A dry/wet etch rate and mechanical strength can becontrolled by using multiple materials for the hardmask at a certainratio, forming a composite film. The preparation of the composite filmcan be performed by at least one of the following: a) alternating a stepof supplying one precursor and a step of supplying a different precursorto form one film on top of another and repeating the steps; b)depositing a film by supplying a mixed precursor containing multipleprecursors; and c) depositing a film by separately supplying multiplediscrete precursors simultaneously. The deposition temperature may beless than 300° C. when the template is constituted by amorphous carbon,or less than 150° C. when the template is constituted by photoresist.

8) The hardmask contains a metal whose fluoride is not solid at areactor-cleaning temperature, e.g., less than 400° C., so that anunwanted film deposited on an inner wall of the reactor can easily beremoved by a fluorine-containing cleaning gas.

Some embodiments will be explained below, but the embodiments are notintended to limit the present invention.

The metal oxide hardmask is constituted by an oxide of Ti, W, and/or Ta.In some embodiments, an oxide of Mn, Hf, and/or Ru can be used in placeof or in combination with Ti, W, and/or Ta. However, preferably,titanium oxide, tungsten oxide, and/or tantalum oxide in view ofmaterial compatibility with semicondutor processing. The hardmask isdeposited by ALD, preferably PE-ALD. For example, a precursor fortitanium oxide can be at least one compound selected from titaniumalkoxide and alkylamino titanium, including Ti(OR)₄ wherein R isindependently CxHy (x=0, 1, 2, 3, 4, or 5, y=2x+1), and each R can bedifferent (e.g., Ti(OCH₃)₂(OC₂H₅)(OC₃H₇)); Ti(NR₂)₄ wherein R isindependently CxHy (x=0, 1, 2, 3, 4, or 5, y=2x+1), and each R can bedifferent (e.g., Ti(N(CH₃)(C₂H₅))₄). A precursor for a metal oxide otherthan titanium oxide can also be selected from any suitable compounds. Ingeneral, an alkylamino precursor such as tetrakis-dimethylaminotitanium(TDMAT) can provide a higher film growth rate than does an alkoxyprecursor such as titanium tetraisopropoxide (TTIP) because a precursorhaving a smaller molecular size such as TDMAT tends to have lesssterific hindrance so as to have more adsorption sites as compared witha precursor having a greater molecular size such as TTIP. Since ALD is aself-limiting adsorption reaction process, the amount of depositedprecursor molecules is determined by the number of reactive surfacesites and is independent of the precursor exposure after saturation, anda supply of the precursor is such that the reactive surface sites aresaturated thereby by each pulse. The deposition temperature may be in arange of about 0 to about 200° C., which temperature is compatible withphotoresist (e.g., does not cause thermal damage to photoresist). Areactant gas may be selected from the group consisting of O₂, NH₃, N₂O,and/or H₂. More than one reactant gas can be used for forming a metaloxide hardmask. A reactant gas flow rate may be in a range of about 100to about 5,000 sccm. A carrier gas for the precursor may be in a rangeof about 200 to about 5,000 sccm. A deposition pressure may be in arange of about 100 to about 1,000 Pa. RF power may be in a range ofabout 50 to about 500 W for direct plasma, or more than 1 kW for remoteplasma. A precursor bottle (or tank) temperature and delivery line maybe controlled at a temperature of about 0 to about 200° C. In someembodiments, reaction energy can be supplied not only by means of plasmaignition, but also by means of UV irradiation.

Additionally, certain treatment can be performed before or during thedeposition process, wherein treatment gas may be selected from the groupconsisting of O₂, NH₃, H₂, N₂, N₂O, He, and/or Ar.

The reactor temperature can be set differently (e.g., higher than thatset for deposition) for reactor cleaning in order to increase cleaningspeed.

In some embodiments, SDDP can be performed as follows:

FIGS. 4A to 4G schematically illustrate SDDP processes. First,pre-patterned features 41 (e.g., photoresist) are formed on a base film(hardmask or BARC) 42 as shown in FIG. 4A. Next, an integrated spacerfilm 43 (which is also referred to generally as “hardmask”) which is aconformal film is deposited according to any of the disclosedembodiments to cover the pre-patterned features 41 and the base film 42as shown in FIG. 4B. The integrated film spacer has a desired ratio ofthickness at the top to thickness at the bottom. A spacer will be a filmlayer formed on a sidewall of the pre-patterned feature 41. In order toform a spacer, anisotropic spacer etching is conducted as shown in FIG.4C to remove all the film material on the bottom surface and the topsurface including the slanted surfaces, i.e., all the horizontalsurfaces and slanted surfaces at the top, leaving only the material onthe sidewalls (43 a). Because the thickness of the film at the slantedsurfaces and the thickness of the film at the bottom surface are suchthat portions of the film at the slanted surface and at the bottomsurface are removed by etching nearly at the same time, after removingthe original pre-patterned features 41, complete removal of the residualportion at the top is realized, and only the spacer is left on the basefilm 42 as shown in FIG. 4D. The inner wall 43 b of the spacer does nothave an overhang portion at the top edge. Using the spacer 43 a,anisotropic etching is performed for pattern transfer as shown in FIG.4E, wherein a pattern transfer layer 44 is formed on a substrate 45.Because according to some embodiments, the spacer has sufficient etchselectivity relative to the base film, and no overhang portion isformed, the distance between the top edges of the spacer and thedistance between the vertical portions of the spacer are substantiallyor nearly the same (±20% or less, ±10% or less, or ±5% or less), and thepattern transfer layer (target film) 44 is accurately etched in thevertical direction. According to some embodiments of the presetinvention, the spacer 43 b is less likely to collapse than aconventional spacer during a drying process after rinsing. That is,complete removal of the residual portion is achieved, and criticaldimension (CD) variation can be minimized and a precise width 46 can beobtained as shown in FIG. 4F. Further, according to some embodiments,the spacer can easily be removed by etching as shown in FIG. 4G.Further, when the metal contained in the spacer is subjected tofluoridation when the reactor is cleaned with a fluorine-containing gas,the metal fluoride is not solid at a reactor-cleaning temperature, andthus, it can easily be removed from an inner wall of the reactor.

FIG. 6 is a schematic representation of an apparatus usable in someembodiments. In this example, by providing a pair of electricallyconductive flat-plate electrodes 64, 62 in parallel and facing eachother in the interior 71 of a reaction chamber 63, applying RF power 65to one side, and electrically grounding 72 the other side, a plasma isexcited between the electrodes. A temperature regulator is provided in alower stage (which also serves as the lower electrode 62), and atemperature of a substrate 61 placed thereon is kept constant at a giventemperature. The upper electrode 64 serves as a shower plate as well,and the reactant gas (C) and additive/purge gas (B), if any, areintroduced into the reaction chamber 63 through gas flow controllers181, 182, respectively, and the shower plate. Also the precursor (A) isintroduced into the reaction chamber 63 through a gas flow controller183, a pulse flow control valve 31, and the shower plate. Additionally,in the reaction chamber 63, an exhaust pipe 66 is provided through whichgas in the interior 71 of the reaction chamber 63 is exhausted.Additionally, the reaction chamber is provided with a seal gas flowcontroller (now shown) to introduce seal gas into the interior 71 of thereaction chamber 63. A separation plate for separating a reaction zoneand a transfer zone in the interior of the reaction chamber is omittedfrom this schematic figure. The seal gas is not required but is used insome embodiments for aiding in preventing reaction gas fromcommunicating with the lower part of the chamber below the separationplate.

For the pulse flow control valve 31, a pulse supply valve caneffectively be used for PE-ALD. This apparatus can also be used forPE-CVD. The pulse control valve can be provided for the reactant gas (C)and/or the additive/purge gas (B). Further, RF power can be pulsed. Inthe above, the pulsing of the RF power can be accomplished by adjustinga matching box (not shown). The RF power requires a minimum time periodfor discharging, which is typically as short as 8 msec. Thus, byadjusting the matching box, the duration of the RF power can easily becontrolled at about 0.1 sec, for example.

In some embodiments, the average thickness deposited per cycle may beabout 0.6 nm/cycle to about 1.0 nm/cycle. The pulse supply of theprecursor can be continued until a desired thickness of film isobtained. If the desired thickness of film is about 20 nm to about 100nm, about 20 cycles to about 150 cycles (e.g., about 40 to about 100cycles) may be conducted.

A remote plasma unit can be connected to the apparatus, through which anetching gas or a process gas can be supplied to the interior of theapparatus through the showerhead 64.

As described above in relation to FIG. 1D, the causes of patterncollapsing are expected to be: 1) the template height is too high tomaintain a spacer during subsequent dry etching, 2) the mechanicalproperties of a spacer film are poor, e.g., its elastic modulus andhardness are so low as to cause deformation easily, and 3) thedifference in film stress between the spacer film and the core materialis so great as to result in pattern collapsing. In some embodiments, theabove causes of pattern collapsing can be eliminated by using a spacercomprising, represented by, made predominately of, consistingessentially of, constituted by, or equivalent to any of the metal oxidesexplicitly, necessarily, or inherently disclosed herein. For example, asshown in FIG. 8B, since a metal oxide such as TiO₂ as a hardmask hashigh etch selectivity against an underlying template/hardmask 82, theheight of the hardmask constituted by TiO₂ can be significantly low ascompared to that of a hardmask constituted by SiO (FIG. 8A). In FIG. 8A,since the etch selectivity of the SiO spacer 83 as a template (the SiO₂spacer is not considered to be a hardmask due to its low dry etchresistivity) is not high, the height of the template needs to be great,resulting in a tall vertical spacer in step (a) which corresponds tostep (d) in FIG. 4D (steps (b) to (d) in FIGS. 4B to 4D are referred toas “spacer defined double patterning”). When etching thetemplate/hardmask 82 using the spacer 83 in step (b) to transfer apatter to the template/hardmask 82, the vertical spacer 83 tends to beat least partially collapsed or deformed. If the vertical spacer isdeformed or collapsed, the pattern transfer is not performed accurately,resulting in inaccurate etching of a target layer 81 in step (c). InFIG. 8B, since the metal oxide spacer has high etch selectivity, anetched template for forming the spacer thereon (see, e.g., atemplate/hardmask 91 in step (b) of FIG. 9) can be short and thus can besustained during etching to form a vertical spacer 84 (metal oxidespacer) in step (a). Thus, steps (b) and (c) can be performedaccurately. In some embodiments, preferably, the height of the verticalspacer (i.e., the thickness of a template to be patterned by etching)may be in a range of about 50 nm to about 400 nm, typically about 80 nmto about 200 nm, and the thickness of the vertical spacer may be in arange of about 3 nm to about 60 nm, typically about 5 nm to about 40 nm.Further, the metal oxide spacer has high elastic modulus and hardness(as measured as a film) (preferably an elastic modulus of about 70 GPato about 400 GPa, typically about 100 GPa to about 200 GPa, and ahardness of about 5 GPa to about 20 GPa, typically about 6 GPa to about15 GPa), and thus, the spacer can be sustained during dry etching.

Additionally, the film stress of the metal oxide (as measured as a film)can be controlled by changing the duration of RF application and/or RFpower, and the film stress can be changed from tensile to compressiveand can minimize pattern deformation, so that the difference in filmstress between the spacer film (which constitutes vertical spacers) andthe core material (which is a photoresist material of a templateremaining in spaces surrounded by the vertical spacers in step (d) inFIG. 9) can be minimized, thereby inhibiting pattern collapsing. In someembodiments, the film stress of the spacer film as measured as a planarfilm and the film stress of the core material as measured as a planarfilm may be substantially or nearly the same, or equivalent, or lessthan about 100 MPa, or less than about 50 MPa. The film stresses areequivalent if the differences therebetween are so small as to inhibitpattern collapsing in SDDP, for example. In some embodiments, the filmstress of the template is first determined, and then, a desired filmstress of the spacer is determined, and accordingly, depositionconditions for the spacer are determined to adjust the film stress ofthe spacer to the desired value as a function of RF power and/or theduration of RF power.

In this disclosure, the term “template” refers to a film to be processedsuch as a film subjected to patterning or formation of holes, and theterm “hardmask” refers to a film having high etch resistivity, e.g.,about five times higher than a template to be etched, so that the filmcan effectively protect a certain portion of the template from beingetched. The “hardmask” may be referred to as an “etch mask”.

In some embodiments, the use of nitrogen-containing gas such as NH₃ andN₂ as a reactant gas increases a film growth rate in PEALD for a metaloxide such as TiO₂. Further, the use of nitrogen-containing gas cansignificantly increase wet etch rate (preferably 2 to 20 times,typically 4 to 8 times, higher than the standard thermal oxide), but caneffectively maintain dry etch resistance (as dry etch rate, preferablyabout 1/100 to about 1/5, typically about 1/50 to about 1/10, of that ofthe standard thermal oxide), which are highly beneficial to subsequentspacer removal. In some embodiments, nitrogen-containing gas is used ina flow rate of about 100 sccm to about 2,000 sccm, typically about 200sccm to about 1,000 sccm, typically in combination with oxygen gas(preferably about 200 sccm to about 1,000 sccm). In some embodiments,the flow rate of nitrogen-containing gas is less than 50% of totalreactant gas but more than 10% (typically 20% to 35%).

As discussed above, according to some embodiments, at least one of thefollowing benefits can be realized: By adding low-frequency RF (LRF)(such as about 200 MHz to about 1,000 MHz, typically about 300 MHz toabout 600 MHz) at a power ratio of LRF to total RF of about 1 to about30, film stress can be more effectively controlled. By controllingplasma ignition conditions (e.g., power and/or ignition time per cycle),film stress and wet etch rate can effectively be controlled. By usingnitrogen-containing reactant gas, film properties can effectively betuned or adjusted.

FIG. 9 is a schematic representation of pattern transfer and targetetching using space defined double patterning (SDDP) according toanother embodiment of the present invention, wherein the metal oxidefilm is used as a hardmask between templates to transfer a pattern fromthe first template to the second template. A template/hardmask 91 isused for increasing pattern density (e.g., pitch reduction) in SDDPprocesses. A template/hardmask 82 is used as a hardmask for etching atarget layer 81. A hardmask 92 is used for transferring a pattern fromthe template/hardmask 91 to the template/hardmask 82. In step (a) inFIG. 9, on a bottom antireflective coating (BARC) 94, a photoresistpattern 93 is formed so that the template/hardmask 91 can be etched inthe photoresist pattern in step (b) which is a step of transferring apattern to the template/hardmask 91. In step (c), a metal oxide spacer95 is deposited according to any of the disclosed embodiments orequivalents thereto, followed by etching in step (d) which is a spacerRIE step. By stripping the material of the template/hardmask 91 (aphotoresist material in the core portions 96), vertical spacers areformed in step (e). Steps (e) to (g) in FIG. 9 correspond to steps (a)to (c) in FIG. 8B (although the height of the vertical spacer isexaggerated). That is, in step (f), the pattern is transferred to thetemplate/hardmask 82, and in step (g), the target layer 81 is subjectedto dry etch. In the above, by using a metal oxide according to any ofthe disclosed embodiments or equivalents thereto as the hardmask 92, thepattern can effectively be transferred from the template/hardmask 91 tothe template/hardmask 82. In some embodiments, a planar hardmask such asthe hardmask 92 may be deposited by any of the methods disclosed hereinor equivalents thereof or by pulsed PECVD.

The embodiments will be explained with reference to specific exampleswhich are not intended to limit the present invention. The numericalnumbers applied in the specific examples may be modified by a range ofat least ±50% in other conditions, wherein the endpoints of the rangesmay be included or excluded.

EXAMPLE Example 1

A metal oxide hardmask film was formed on a substrate (Φ200 mm) byPE-ALD under the conditions shown below using the PE-ALD apparatusillustrated in FIG. 6. The sequence in each cycle of PE-ALD is shown inFIG. 7.

TABLE 1 Precursor Titanium tetra-isopropoxide Deposition temperature 50deg C. Reactant gas flow O₂, 500 sccm Carrier gas flow Ar, 2000 sccmDeposition pressure 200 Pa RF power (27.12 MHz) 50 W Deposition processsequence Step 1: Step 2: Step 3: Step 4: Precursor feed Precursor purgeRF ignition Post purge 0.9 sec 2.0 sec 0.5 sec 0.5 sec

A SiO hardmask (LT-SiO) was also formed on a substrate by PE-ALD underconditions substantially the same as above.

Dry etch selectivity and wet etch selectivity of each hardmask (alsothose of standard thermal oxide) were measured, and the results areshown below.

TABLE 2 Thermal oxide PEALD LT-SiO PEALD TiO₂ Dry etch rate 0.20 1.000.11 (NF₃, 100 deg C.) Wet etch rate 0.09 1.00 0.10 (DHF 1:100)

Hardness and Elastic modulus of each hardmask were also measured, andthe results are shown below.

TABLE 3 PEALD LT-SiO PEALD TiO₂ EM (GPa) 41.6 158.7 Hardness (GPa) 3.69.8

As shown in the above tables, the TiO hardmask has substantially highdry/wet etch selectivity relative to that of the LT-SiO hardmask. Thewet etch selectivity of the TiO hardmask was substantially comparable tothat of the standard thermal oxide, and the dry etch rate of the TiOhardmask was substantially lower than that of the LT-SiO hardmask.Further, the mechanical strength of the TiO hardmask was substantiallyhigher than that of the LT-SiO hardmask, indicating that thespacer-collapsing problem can effectively be avoided.

Example 2

In the same manner as described in Example 1 except for the conditionsshown in Table 4 below, films were deposited to compare film growthrates using titanium tetraisopropoxide (TTIP) andtetrakis-dimethylaminotitanium (TDMAT). As can be seen from the table,the film growth rate by TDMAT was nearly two times higher (2-3, 2-4)than that by TTIP (2-1, 2-2). The properties of the obtained film byTDMAT were comparable with those by TTIP, although the wet etch rate ofthe film by TDMAT was increased by about two to three times that byTTIP. Additionally, by prolonging the RF ignition time (2-5), themechanical strength was increased and the wet etch rate was reduced.

TABLE 4 2-1 2-2 2-3 2-4 2-5 Precursor TTIP TTIP TDMAT TDMAT TDMAT RFpower 50 W 100 W 50 W 100 W 100 W RF ignition time per cycle 0.4 sec 0.4sec 0.4 sec 0.4 sec 2.0 sec GPC (nm/cycle) 0.042 0.042 0.079 0.074 0.059RI 2.401 2.407 2.281 2.308 2.415 WER Ratio 0.75 0.84 2.79 1.47 0.64(1:100 DHF) compared to thermal oxide Hardness (GPa) 9.01 9.39 8.10 8.9012.70 EM (GPa) 160.6 167.5 130.2 147.0 190.1 Film stress (MPa, 388.8370.6 226.6 227.8 181.8 Tensile = +) GPC: Growth rate per cycle; RI:Refractive index; WER: Wet etch rate; DHF: Dilute hydrofluoric acid; EM:Elastic modulus

Example 3

In the same manner as described in Example 1 except for the conditionsshown in Tables 5 and 6 below, films were deposited to confirmcontrollability of film stress. As can be seen from Table 6, the filmstress was well controlled by changing plasma-on time (duration of RFignition) and/or plasma power (RF power), indicating that the filmsobtained using TTIP are suitable as a spacer having pattern-collapsingresistance. That is, by increasing the plasma-on time, the degree oftensile stress of the film can be reduced, and by increasing plasmapower, the degree of tensile stress of the film can be reduced and caneven be changed to compressive stress.

TABLE 5 TiO₂ Source TTIP  23 sccm Reactant gas Oxygen  500 sccm Carriergas Ar 2000 sccm Pressure 200 Pa RF power Variable (X) W Source feedPurge 1 Plasma on Purge 2 0.3 sec  0.6 sec Variable (Y) sec 0.1 sec

TABLE 6 Process Precursor Plasma power Plasma-on temperature supply (X)time (Y) Film stress 100 deg C. TTIP  50 W 0.4 sec +388 MPa 100 deg C.TTIP  50 W 2.0 sec +161 MPa 100 deg C. TTIP 100 W 0.4 sec +275 MPa 100deg C. TTIP 300 W 0.4 sec −268 MPa

Example 4

In the same manner as described in Example 1 except for the conditionsshown in Table 7 below, films were deposited to evaluate effects of NH₃on properties of the films.

As can be seen from Table 5 below, when adding NH₃ to oxygen as areactant (4-3, 4-4), the film growth rate was increased (by over 20%),and the dry etch rate of the film was significantly decreased (by over70%), whereas the wet etch rate of the film was surprisingly increased(by over 600%) as compared with that without NH₃ (4-1, 4-2), indicatingthat the film is suitable as a spacer which has chemical resistance butis easily removable. Additionally, the properties of the films obtainedusing less NH₃ (4-3) and more NH₃ (4-4) than oxygen appear to besimilar.

TABLE 7 Precursor: TTIP 4-1 4-2 4-3 4-4 Process condition O₂ 500 sccm O₂1000 sccm O₂ 500 sccm O₂ 500 sccm NH₃ 0 sccm NH₃ 0 sccm NH₃ 250 sccm NH₃1000 sccm GPC (nm/cycle) 0.042 0.042 0.055 0.052 RI 2.401 2.407 2.1792.177 WER Ratio 0.75 0.84 6.38 5.45 (1:100 DHF) compared to thermaloxide DER Ratio 0.24 0.27 0.07 0.06 (100° C. NF₃) compared to thermaloxide Hardness (GPa) 9.01 9.39 6.79 6.82 EM (GPa) 160.6 167.5 114.5113.7 Film stress (MPa, 388.8 370.6 312.4 303.3 Tensile = +)

Example 5

In addition to Example 1, SiN hardmasks were formed by PE-ALD at 400° C.and at 100° C., respectively, and a TEOS hardmask was also formed byPE-ALD at 380° C., according to conventional recipes, and the mechanicalstrength of the resultant hardmasks was measured. The results are shownin FIG. 5. As can be seen from FIG. 5, the TiO hardmask has asubstantially higher elastic modulus than that of the SiN hardmask at100° C. and the TEOS hardmask, and the hardness of the TiO hardmask iscomparable to that of the SiN hardmask at 100° C. and the TEOS hardmask.Since the TiO hardmask has a significantly high elastic modulus, thespacer collapse problem can effectively be avoided (elastic modulus ismore important than hardness in terms of prevention of spacer collapse).Additionally, the TiO hardmask has significant advantages as comparedwith the SiN hardmask at 100° C. and the TEOS hardmask in terms ofdeposition rate, conformality, etch selectivity, etc. For example, theSiN hardmask at 100° C. has a good etch selectivity relative to a basefilm, but it is not easy to remove by etching. The TEOS hardmask doesnot have a good etch selectivity relative to a base film. The SiNhardmask at 400° C. has higher mechanical strength than the TiOhardmask. However, the deposition temperature of 400° C. causes thermaldamage to a template or photoresist, and further, copper or other metaldiffusion or migration is likely to be a problem. Further, removing theSiN hardmask at 400° C. is not easy, and even at 400° C., the depositionrate is low. In view of the above, the TiO hardmask is significantlysuperior to the other hardmasks.

Example 6

In the same manner as in Example 5 except for the conditions shown inTable 8 below, films were deposited to evaluate elastic modulus andhardness of the films. As can be seen from the table, a film of TiO₂shows excellent elastic modulus even though the deposition temperaturewas low, and also the film shows as good hardness as a SiN film andsignificantly better hardness than a SiO film.

TABLE 8 Material Elastic Modulus Hardness TiO₂ PEALD 100 deg C. 175 GPa10.3 GPa SiO PECVD 380 deg C.  80 GPa 10.3 GPa PEALD  75 deg C. 45.3GPa  4.3 GPa ALD 450 deg C. 56.4 GPa  5.1 GPa SiN PEALD 100 deg C. 108GPa 11.7 GPa PEALD 400 deg C. 243 GPa 31 GPa

Example 7

In the same manner as in Example 1 except for the conditions shown inTable 9 below, films were deposited to evaluate refractive index (at 633nm) and average growth rate (nm/cycle) of the films, wherein an ALDcycle ratio of the number of cycles for TiO₂ to the total number ofcycles for TiO₂ and SiO₂ per unit cycle for one layer of multi-elementfilm was changed from 0/1 to 1/1 (i.e., 0/1, 1/3, 1/2, 2/3, and 1/1). Inthe above, a ratio of 1/3 refers to a unit cycle constituted by two SiO₂cycles, followed by one TiO₂ cycle; a ratio of 1/1 refers to a unitcycle constituted by one SiO₂ cycle, followed by one TiO₂ cycle; and aratio of 2/3 refers to a unit cycle constituted by one SiO₂ cycle,followed by two TiO₂ cycles, wherein each unit cycle was repeated atdesired times.

TABLE 9 SiO₂ cycle Source BDEAS  26 sccm Reactant gas Oxygen  500 sccmCarrier gas Ar 2000 sccm Pressure 200 Pa RF power 100 W Source feedPurge 1 Plasma on Purge 2 0.3 sec  0.6 sec   0.4 sec  0.1 sec TiO₂ cycleSource TTIP  23 sccm Reactant gas Oxygen  500 sccm Carrier gas Ar 2000sccm Pressure 200 Pa RF power 100 W Source feed Purge 1 Plasma on Purge2 0.3 sec  0.6 sec   0.4 sec  0.1 sec

As shown in FIG. 10, it was confirmed that by changing the ALD cycleratio (e.g., in any ranges defined by any two values of the above ratiosor any two numbers of 0.1 to 0.9 in 0.1 increments), the refractiveindex and the growth rate of the resultant films could be adjusted atdesired levels, although the relationship between the refractive indexand the ALD cycle ratio and the relationship between the growth rate andthe ALD cycle ratio were reversed.

The present invention can include, but is not limited to, the followingadditional embodiments and advantages:

In order to avoid spacer collapse, mechanically robust materials otherthan those disclosed above can be used.

In order to avoid spacer collapse, footing reduction can be performed.FIGS. 3A and 3B is a schematic representation illustrating in-situfooting reduction where (a) reactive ion etch (RIE) (FIG. 3A) and (b)ashing (FIG. 3B) are conducted. In step (a), a spacer film is depositedby PE-ALD on a photoresist and a base film, and in-situ interfacecontrol is conducted, thereby performing in-situ footing reduction ofthe spacer film, wherein a top surface of a photoresist 33 and a part ofa base film 31 are exposed, and a spacer 32 does not have extendedfooting. In step (b), by ashing, the photoresist 33 is removed, therebyforming the spacer 32′ having reduced footing, decreasing CD changes.The metal oxide hardmask selected in some embodiments of the presentinvention is effective for footing reduction.

In order to avoid spacer collapse, adhesion between the spacer and thebase film can be enhanced. Enhancing adhesion can be accomplished byforming an adhesion layer or treating a surface of the base film. Themetal oxide hardmask selected in some embodiments of the presentinvention is effective for enhancing adhesion.

All processes can be done sequentially in one PE-ALD reactor, includingpre-bake, trimming, adhesion control, deposition and surface control,thereby achieving high productivity and low cost.

Dry etch rate and mechanical strength can be controlled by combiningmultiple materials.

In-situ reactor self cleaning can be performed by selecting a metalwhose fluoride has high vapor pressure at room temperature (unlikeAlF₃), thereby achieving high productivity and low cost. The metal oxidehardmask selected in some embodiments of the present invention iseffective for easy self cleaning.

The deposition process is ALD so that 100% conformality, less patternloading, and good uniformity can effectively be achieved.

Since ALD dielectric materials have been widely studied, it is possibleto select good candidate materials without undue burden by using atleast one or all of the criteria disclosed in the embodiments.

Generally, thermal ALD is very challenging at low temperatures such asless than 400° C. because chemical reactivity decreases withtemperature. PE-ALD is advantageous at low temperatures, and a conformalfilm can be formed. Unlike thermal ALD, PE-ALD can deposit differentmaterials on a substrate at the same temperature. Also for this reason,PE-ALD is advantageous. Thermal reaction cannot effectively control filmcomposition and precursor adsorption. PE-ALD can control each filmquality by tuning process conditions. Good process controllability andgood process reliability can be realized by using PE-ALD. Incidentally,a catalyst used as an aid of deposition is usually not useful in eitherthermal or PE-ALD, and thus, no catalyst is used.

A preferred metal oxide is expressed by Si_(x)Ti_((1-x))O_(y) whereinO≦x<1, y˜2. A WO or TaO hardmask can be used. Additionally, a TiN, WN,or TaN hardmask may be used in combination with those disclosed herein.

It will be understood by those of skill in the art that numerous andvarious modifications can be made without departing from the spirit ofthe present invention. Therefore, it should be clearly understood thatthe forms of the present invention are illustrative only and are notintended to limit the scope of the present invention.

We claim:
 1. A method of forming a metal oxide hardmask on a template,comprising: providing a template constituted by a photoresist oramorphous carbon formed on a substrate; and depositing by atomic layerdeposition (ALD) a metal oxide hardmask on the template constituted by amaterial having a formula Si_(x)M_((1-x))O_(y) wherein M represents atleast one metal element, x is less than one including zero, and y isapproximately two or a stoichiometrically-determined number, wherein themetal oxide hardmask is constituted by a laminate of atomic layers of ametal oxide and atomic layers of a silicon oxide alternately depositedat a cycle ratio C such that the laminate has the formulaSi_(x)M_((1-x))O_(y), where C=m/(m+n) where m is the number of cyclesfor metal oxide consecutive layers, and n is the number of cycles forsilicon oxide consecutive layers.
 2. The method according to claim 1,wherein the cycle ratio is adjusted in a range of over 0/1 and less than1/1.
 3. The method according to claim 1, wherein the metal oxidehardmask is a spacer film.
 4. The method according to claim 3, whereinthe spacer film is for spacer-defined double patterning (SDDP), and themethod further comprises performing SDDP after the step of depositingthe spacer film on the template.
 5. The method according to claim 1,wherein M is a metal whose fluoride has a vapor pressure of more than100 Pa at a temperature for cleaning a reactor used for depositing themetal oxide hardmask.
 6. The method according to claim 5, wherein M isTi, W, or Ta.
 7. The method according to claim 6, wherein M is Ti. 8.The method according to claim 7, wherein the material constituting themetal oxide hardmask is TiO₂.
 9. The method according to claim 1,wherein the ALD is plasma enhanced ALD (PE-ALD).
 10. The methodaccording to claim 1, wherein the ALD is performed at a temperature of300° C. or lower for the template constituted by the amorphous carbon orat a temperature of 150° C. or lower for the template constituted by thephotoresist.
 11. The method according to claim 1, wherein the ALD isperformed under conditions substantially equivalent to those set for aSiO₂ hardmask constituted by SiO₂, wherein a gas containing M is used inplace of a gas containing Si for the SiO₂ hardmask.
 12. The methodaccording to claim 11, wherein the metal oxide hardmask has an elasticmodulus at least three times higher than that of the SiO₂ hardmask, anda hardness at least two times higher than that of the SiO₂ hardmask. 13.The method according to claim 11, wherein the metal oxide hardmask has adry etch rate lower than that of the SiO₂ hardmask and a wet etch ratecomparable to that of standard thermal oxide.
 14. The method accordingto claim 1, wherein the substrate has a base film formed under thetemplate, which base film is constituted by silicon oxide.
 15. Themethod according to claim 1, wherein the template has a convex patternconstituted by the photoresist or amorphous carbon, said convex patternhaving a width of less than one micron meter and a ratio of height towidth of one or higher.
 16. The method according to claim 9, wherein thedepositing of the metal oxide hardmask comprises supplying a precursorfor the metal oxide hardmask in pulses and applying RF power in pulsesbetween the pulses of the precursor, wherein at least one reactant gasis supplied while applying the RF power, wherein the precursor is ametal-containing alkylamino compound or metal-containing alkoxycompound.
 17. The method according to claim 16, wherein the reactant gascomprises a nitrogen-containing gas.
 18. A metal oxide hardmaskdeposited on a template, constituted by a material having a formulaSi_(x)M_((1-x))O_(y) wherein M represents at least one metal elementselected from Ti, W, or Ta, x is more than zero but less than one, and yis approximately two or a stoichiometrically-determined number, whereinthe metal oxide hardmask is constituted by a laminate of atomic layersof a metal oxide and atomic layers of a silicon oxide alternatelydeposited at a cycle ratio C such that the laminate has the formulaSi_(x)M_((1-x))O_(y), where C=m/(m+n) where m is the number of cyclesfor metal oxide consecutive layers, and n is the number of cycles forsilicon oxide consecutive layers.
 19. The metal oxide hardmask accordingto claim 18, wherein the metal oxide is TiO₂, and the silicon oxide isSiO₂.
 20. The metal oxide hardmask according to claim 18, wherein theproportion of metal oxide relative to the mixture of metal oxide andsilicon oxide varies in a thickness direction of the laminate as thecycle ratio varies.